. >> president obama faced the white house press corps tuesday and a deluge of questions on national security. with the tax on the boston marathon still so raw, he addressed criticism that the u.s. did not do enough to prevent the bombings. >> it's not as if the fbi did nothing. they not only investigated the older brother, they interviewed the older brother. they concluded that there were no signs that he was engaging in extremist activity. >> questions touched on security threats overseas and evidence the chemical weapons may have been used. president obama says he needs information before he can make a decision on military action. >> the use of chemical weapons would be a game changer. not only for the united states, but for the international community. >> the president maintains guantanamo bay is not necessary and should be closed. >> it is expensive. it is inefficient. it hurts us in terms of our international standing. >> the president seemed cautiously hopeful about a potential compromise on fiscal legislation. >> things that compromise me is somehow a betrayal. they are worri